1. Field of the Invention
The present invention relates to a direct-injection type diesel engine and more particularly to an engine which can prevent overheat of a glow plug.
2. Description of Prior Art
There is a conventional engine which comprises a cylinder head with a fuel injection nozzle and a glow plug attached thereto like the present invention, as a direct-injection type diesel engine.
However, the conventional type of engine has a glow plug extending through an exhaust port wall portion.
According to the conventional technique, exhaust air passing through an exhaust port has its heat easily transmitted to the glow plug with the result of readily overheating the glow plug.
The present invention has an object to provide a direct-injection type diesel engine capable of solving the foregoing problem.
The contents of the present invention is as follows.
It is a direct-injection type diesel engine, as shown in FIG. 1, which comprises a cylinder head 1 with a fuel injection nozzle 2 and a glow plug 3 attached thereto.
The fuel injection nozzle 2 has a leading end opposed to a cylinder mid portion 4 and the glow plug 3 extends through an intake port wall portion 6 between the fuel injection nozzle 2 and an intake port 5. The glow plug 3 is inclined with respect to the fuel injection nozzle 2 by a predetermined angle (xcex81) and has a leading end inserted into the cylinder mid portion 4.
The present invention offers the following effect.
xe2x80x9cEffect 1xe2x80x9d It is Possible to Inhibit the Overheat of the Glow Plug.
As shown in FIG. 1, the glow plug extends through the intake port wall portion 6 between the fuel injection nozzle 2 and the intake port 5. Therefore, exhaust air passing through an exhaust port 11 has its heat hardly transmitted to the glow plug 3. This results in the possibility of preventing the overheat of the glow plug 3.
xe2x80x9cEffect 2xe2x80x9d It is Possible to Uniformly Heat a Combustion Chamber Over its Entirety.
As shown in FIG. 1, the glow plug 3 has its leading end inserted into the cylinder mid portion 4 with the result of being able to uniformly heat the whole combustion chamber.
xe2x80x9cEffect 3xe2x80x9d It is Easy to Insert the Glow Plug.
As shown in FIG. 1, the glow plug 3 is inclined with respect to the fuel injection nozzle 2. Therefore, it is possible to insert the leading end of the glow plug 3 into the cylinder mid portion 4 without causing the glow plug 3 to interfere with the fuel injection nozzle 2. This makes it easy to insert the glow plug 3.
xe2x80x9cEffect 4xe2x80x9d A Swirl is Strengthened in the Combustion Chamber.
As shown in FIG. 1, in the case of forming a wedge-like port portion 5a which increase its width toward intake valve ports 10a, 10b, intake air passing through the intake port 5 is strongly pushed into the intake valve ports 10a,10b as shown in FIG. 2, while being pressed to an opposite wall 8a in the wedge-like port portion 5a. This allows high-speed intake air to flow into an inner peripheral surface side portion of a cylinder 21 to result in strengthening the swirl within the cylinder 21.
xe2x80x9cEffect 5xe2x80x9d It is Possible to Inhibit the Overheat of the Fuel Injection Nozzle.
As shown in FIGS. 1 and 2, the intake port wall portion 6 is projected to provide a nozzle boss 6a through which the fuel injection nozzle 2 is inserted. This arrangement makes it hard for the heat of the exhaust air passing through the exhaust port 11 to be transmitted. Thus it is possible to prevent the overheat of the fuel injection nozzle 2.
xe2x80x9cEffect 6xe2x80x9d The Overheat of the Glow Plug is Inhibited.
As shown in FIG. 2, the intake port wall portion 6 through which the glow plug 3 extends opposes to an inter-port transverse water passage 12. This arrangement inhibits the overheat of the glow plug 3.
xe2x80x9cEffect 7xe2x80x9d Intake Air is Filled With a High Efficiency.
As shown in FIG. 2, cooling water which passes through the inter-port transverse water passage 12 is arranged to flow from the intake air distributing means 13 to the exhaust air converging means 14. This arrangement makes it hard for the exhaust air heat to be transmitted to the intake air distributing means and can prohibit the intake air from increasing its temperature. Thus intake air is filled with a high efficiency.
xe2x80x9cEffect 8xe2x80x9d It is Possible to Inhibit Leakage of the Glow Plug.
As shown in FIG. 1, the glow plug 3 has a terminal projected out of the head cover 15. This arrangement removes a likelihood that condensed water, oil mist and the like within the head cover 15 adhere to the terminal, with the result of being able to inhibit the leakage of the glow plug 3.
xe2x80x9cEffect 9xe2x80x9d It is Possible to Secure a Large Volume of a Breather Chamber.
As shown in FIG. 5, when seen in a direction parallel with the cylinder center axis 7, the intake port wall portion 6 through which the glow plug 3 extends is displaced in a direction opposite to a direction in which the breather chamber 20 is deviated from a center axis 17 of a crank shaft. Owing to this arrangement, the breather chamber 20 can expand into the direction opposite to the deviated direction without being interrupted by the glow plug 3 which extends through the head cover 15. This results in the possibility of securing a large volume of the breather chamber 20.